Why?

Extinct mosquitoes is a platform born in 2019 with three main goals:

1. Acknowledge the emergency

To raise awareness about the urgency and magnitude of the mosquito-borne diseases problem. They are one of humanity’s greatest challenges, and they should be given the same importance as the fight against hunger, wars and climate change among others.

2. Educate

To inform and educate the population on the risks and benefits of using the gene drive technology for solving this issue.

3. Call to action

To provide the tools for everyone to be part of the solution and spread the word. To encourage governments and other organizations to cooperate, implement policies and provide funding aimed at the eradication of the most dangerous mosquito species.

Why do we have to eradicate mosquitoes? Could there be a better solution?

There are, of course, more ways to fight mosquito-borne diseases. However, none of them have proved to be as effective as completely eliminating the disease vector:

Such as bed nets, pesticides or larvae control. They have been useful in reducing the incidence and mortality of malaria. The World Health Organization estimated that 839,000 people died from malaria in the year 2000, while in 2018 this number drastically decreased to 405,000 deaths.(1)

But traditional mosquito control efforts have not been as successful in the prevention of other diseases. For example, dengue cases are exponentially growing every year, and nowadays 50% of the world population is at risk of contracting this disease.(2) In 2019, the Pan American Health Organization announced that it had recorded the highest number of dengue cases in the history of America.(3)

The same goes for other arboviruses such as chikungunya, Zika or the West Nile virus, whose incidence has been steadily increasing in the last decades.(4)(5)


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References:                                                                                                                                                                                                                       

1. https://www.who.int/publications-detail/world-malaria-report-2019
2. https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue
3. https://www.paho.org/hq/index.php?option=com_content&view=article&id=15593:dengue-in-the-americas-reaches-highest-number-of-cases-recorded&Itemid=1926&lang=en
4. Gould, E., Pettersson, J., Higgs, S., Charrel, R., & de Lamballerie, X. (2017). Emerging arboviruses: Why today?. One health (Amsterdam, Netherlands), 4, 1–13. https://doi.org/10.1016/j.onehlt.2017.06.001
5. Espinal, M. A., Andrus, J. K., Jauregui, B., Waterman, S. H., Morens, D. M., Santos, J. I., Horstick, O., Francis, L. A., & Olson, D. (2019). Emerging and Reemerging Aedes-Transmitted Arbovirus Infections in the Region of the Americas: Implications for Health Policy. American journal of public health, 109(3), 387–392. https://doi.org/10.2105/AJPH.2018.304849

New drugs have also helped to lower the number of malaria and lymphatic filariasis infections.(6) However, it has been proved difficult to provide access to these medicines in low- and middle- income countries.(7) On top of that, many strains of the malaria parasite have developed resistance to them,(8) and the design of new effective drugs is a very costly and lengthy process.

There is no specific treatment available for other mosquito borne diseases like dengue,(9) chikungunya(10) or Zika.(11) Only palliative care can be used for relieving the symptoms: getting plenty of rest, drinking fluids and taking acetaminophen (Tylenol®).

 

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References:

6. Mathew, C. G., Bettis, A. A., Chu, B. K., English, M., Ottesen, E. A., Bradley, M. H., & Turner, H. C. (2019). The health and economic burden of lymphatic filariasis prior to mass drug administration programmes. Clinical Infectious Diseases.
7. Barton, I., Avanceña, A., Gounden, N., & Anupindi, R. (2019). Unintended Consequences and Hidden Obstacles in Medicine Access in Sub-Saharan Africa. Frontiers In Public Health, 7. https://doi.org/10.3389/fpubh.2019.00342
8. Tse, E., Korsik, M., & Todd, M. (2019). The past, present and future of anti-malarial medicines. Malaria Journal, 18(1). https://doi.org/10.1186/s12936-019-2724-z
9. https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue
10. https://www.who.int/news-room/fact-sheets/detail/chikungunya
11.https://www.who.int/news-room/fact-sheets/detail/zika-virus

The yellow fever vaccine is the only one that is highly effective (+99% immunisation after one dose) and widely used. It has been available since the late 1930s,(12) and yet it is estimated that in the year 2013, yellow fever killed between 29,000 and 60,000 people all around the world.(13)

The development of useful vaccines for the rest of mosquito-borne illnesses has been proved to be extremely challenging.(*) And unfortunately, even if new vaccines were discovered, yellow fever has proved that they will not straightaway solve all of our problems.

(*)
-In May 2019, the first vaccine against dengue was approved by the FDA (Dengvaxia®). However, this approval was very limited: only individuals from 9 to 16 years of age who have been previously affected by dengue should be vaccinated.(14)

-In 2019 as well, a pilot study was launched in Ghana, Kenya and Malawi, to help the World Health Organization to decide if the world’s first malaria vaccine (RTS,S) is effective enough to be deployed in more countries. For now, it has proved that after four doses the cases of malaria in children aged 5–17 months were reduced by 39% (equivalent to preventing nearly 4 in 10 malaria cases).(15)
(*)

 

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References:

12. Collins, N. D., & Barrett, A. D. (2017). Live Attenuated Yellow Fever 17D Vaccine: A Legacy Vaccine Still Controlling Outbreaks In Modern Day. Current infectious disease reports, 19(3), 14. https://doi.org/10.1007/s11908-017-0566-9
13. https://www.who.int/news-room/fact-sheets/detail/yellow-fever
14. https://www.fda.gov/vaccines-blood-biologics/dengvaxia
15. https://www.who.int/malaria/media/rtss-phase-3-trial-qa/en/

Wolbachia is an intracellular bacteria that affects insects, and it’s generally passed from an infected female to all her offspring.(16) It has been observed that mosquito populations that carry a certain strain of this bacteria have a boosted immune response, and thus they are less likely to transmit diseases such as Zika,(16) dengue and chikungunya.(17)

This is a novel and very promising technology that is being already implemented in many cities around the world.(18) Still, we have to keep in mind that this method is aimed at reducing disease transmission, not eliminating it. Furthermore, it’s long-term effectivity is not well known yet.(19)

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References:

16. Chouin‐Carneiro, T., Ant, T., Herd, C., Louis, F., Failloux, A., & Sinkins, S. (2019). Wolbachia strain wAlbA blocks Zika virus transmission in Aedes aegypti. Medical And Veterinary Entomology, 34(1), 116-119. https://doi.org/10.1111/mve.12384
17. Moreira, L., Iturbe-Ormaetxe, I., Jeffery, J., Lu, G., Pyke, A., & Hedges, L. et al. (2009). A Wolbachia Symbiont in Aedes aegypti Limits Infection with Dengue, Chikungunya, and Plasmodium. Cell, 139(7), 1268-1278. https://doi.org/10.1016/j.cell.2009.11.042
18. https://www.worldmosquitoprogram.org/en/global-progress
19. https://www.worldmosquitoprogram.org/en/learn/faqs

A gene drive system could also be used to confer immunity to mosquitoes against diseases.(20) The main advantage of this approach is that there is no need to eliminate mosquitoes, so the chance of harming the ecosystem is lower.

However, it could have some unintended negative consequences too. By making mosquitoes resistant to diseases, we favour the emergence of more aggressive pathogen strains.(21) On top of that, this is a very technically-challenging procedure that still needs many years of research before being put into practice.

 

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References:

20. Marshall, J., & Akbari, O. (2016). Genetic control of malaria and dengue (pp. 169-200). https://doi.org/10.1016/B978-0-12-800246-9.00009-0
21. Marshall, J., Raban, R., Kandul, N., Edula, J., León, T., & Akbari, O. (2019). Winning the Tug-of-War Between Effector Gene Design and Pathogen Evolution in Vector Population Replacement Strategies. Frontiers In Genetics, 10. https://doi.org/10.3389/fgene.2019.01072

Despite its potential risks, we consider that the eradication of harmful mosquito species is the most robust and cost-effective solution to the mosquito borne disease problem.